A heat exchanger for the cooling system of an internal combustion engine for an automotive vehicle utilizes an inlet tank or header and an outlet tank or header connected by a radiator core to provide for either downflow or crossflow circulation of the coolant between the tanks. The inlet tank normally has a coolant inlet, a supply and overflow fitting for a pressure cap, and an overflow conduit, and the outlet tank has a coolant outlet. The radiator core comprises a plurality of parallel spaced tubes extending either vertically or horizontally between the inlet and outlet tanks and a plurality of convoluted fins located in the spacing between the tubes.
In the alternative, a stack of horizontally or vertically oriented flat plate-type fins may form the core with the generally vertical or horizontal tubes, respectively, wherein each fin has a plurality of openings receiving the tubes therethrough. Either type of fin is in contact at a plurality of points with the tubes to provide heat transfer from the hot fluid passing through the tubes to air circulating between the tubes and around the fins; the fins acting to increase the surface area in contact with the air stream and enhance the heat transfer. Also, the convoluted fins may be utilized in a plate-fin separatar type of heat exchanger.
To further improve the heat transfer characteristics of the heat exchanger, the fins have been formed with opening, tabs or louvres to increase turbulance of the air stream passing through the radiator core. The louvres act to increase the heat transfer from the fins to the air flowing around the tubes and fins. In substantially all radiator cores, whether of the corrugated fin or of the slit plate fin type, there is an overhang of the fin beyond the row or rows of tubes. When the slitting of the louvres stops close to the edge of the fin in the overhanging portion beyond the tubes, the heat flow to the overhanging fin portion is restricted. The present invention provides fin and louvre designs to overcome this problem.